Glue



Patented Jan. 17, 1950 Delhi, La., assignors to Chicago M ll and-Lum ber Company, Chicago, 111., a corporation of Delaware No Drawing. Application February {6, 1948, Serial No. 6,813

6 Claims.

This invention relates to a cold-setting adhesive or glue which is applied in a water vehicle and yet has excellent Water-resisting properties when set.

Specifically, the invention deals Withfan adhesive of the alkalinized ,proteinous vegetable fiour type which is fortified with a particular type of residual resin from wood to impart unique properties to the adhesive.

Alkalinized proteinous vegetable flour glues, such as soya bean glues, locust been glues, cottonseed glues, linseed glues, and the like known adhesives-are deficient when utilized on very wet materials and when required in appreciable amounts on flat surfaces. These prior known glues are relativelyfree fiowing and willnot remain in thick film form :on extensive surfaces, such as the broad faces of paper or Wood veneer.

In accordance with the present invention, disadvantages of heretofore known alkalinized proteinous vegetable flour glues are avoided by addition of a residual resin from wood which issubstantially freed of Wood rosin. The resin, unlike wood rosin, is substantially insolubleiin light petroleum hydrocarbons such as gasoline. A suitable residual resin is known to the trade under the trade-mark Vinsol, and has a melting point by the drop method of 115 C., an acid number of 93, and a .methoxy content between 3 to 6%. It is obtained by extracting southern long-leaf pine wood. with a coal tar hydrocarbon to .produce a coal tar hydrocarbon extract containing turpentine, pine oil, rosin, and a residue. Volatiles are removed from the extract by evaporation, and resin is then separated from the residue by means of gasoline in which it is soluble. The gasoline-insoluble residual material is Vinsol.

Thephrase residual resin from wood, as used herein, therefore refers to "the resin typified by that product remaining from the extract obtained by treating southern long-leaf pine wood *with coal tar hydrocarbons after the extractis freed substantially from gasoline solubles such as wood rosin.

It is, then, an object of this inventionto provide a glue containing an alkalinized vegetable protein and a residual resin from wood that makes the glue tacky.

Another object of the invention is to provide a water-resisting glue containing soya beanflour and the residual resin remaining after a coal tar hydrocarbon extract of wood has been substantially freed of wood rosin by means of gasoline.

Another object of the invention is toprovide a water-resisting adhesive containing alkalinized vegetable protein flour and Vinsol.

A still further object of theinventionis toprovide a glue adapted to draw togetherandinte grally bond paper and wet wood, making possible the use of inferior grades of wood without loss of efiiciency of the paper-covered wood product.

, Other and further objects of the invention will become more apparent to those skilled in the art from the following detailed descriptions and examples.

In the preparation of pa er-covered wood veneer for which the glue of this invention is especially suitable, undried green wood is peeled or lathe-cut in the conventional manner to form veneer sheets of the desired thickness. These veneer sheets are connected in end to end relation to form a continuous ribbon. Tough, water-absorbent paper, such as unsized kraft paper, is unreeled from rolls which are respectively positioned over and under the continuous ribbon of veneer. Coating machines apply glue to one face of each of the paper sheets from these rolls and the glue-coated faces of the paper are then doposited on the veneer ribbon as it advances. Pressure rolls firmly squeeze the paper against the wood to insure intimate contact between the wood and the glue-coated faces of the paper. The glue bonds the paper to the wood before the wood is driedto apoint whereshrinkage can occur. After the firm integral bond has been formed, the paper-covered veneer is dried so that the paper and wood simultaneously lose their moisture. However, during the drying operation, the paper, which has previously been firmly bonded to the wood, holds the wood in the expanded, swollen condition of its wet state even after the wood loses its moisture. Since wood does not begin to shrink until its moisture content is reduced below about 30 lbs. of water per lbs. of dry wood (30% moisture content) the glue bond is formed before the wood is dried below 30%.

The glue of this invention, which is especially useful for forming the glue bond in the abovediscussed method of making paper-covered wood veneer, is relatively tacky and sticky, so that it can be applied in sufficient quantity to the kraft paper and remain thereon in film formuntil the paper is applied to the wood. Heretofore, vegetable protein glues have been non-tacky and smooth, rendering it difi'icult to maintain the desired glue content on a flat surface. In addition, the glues of this invention liberate their water content and wet the paper at a much faster rate than heretofore known vegetable protein glues. This feature makes possible the speeding up of production of paper-covered wood, because the glue sets in the cold state to firmly bond'the paper to the wood at a much faster rate and without requiring drying 'of the wood to its shrinking point.

glues bridged across such irregularities and blisters resulted in the finished paper-covered veneer product. Under the circumstances, lower quality Veneer woods can now be used without showing defects through the paper to the surface of the finished product.

The glues of this invention also lengthen the working life of vegetable protein glues by maintaining them in a free-flowing spreadin condition for a longer period of time. Heretofore, alkalinized vegetable protein flour glues tended to set up into lumpy masses, necessitatin small batch preparation and quick application.

The glues of this invention also make possible,

in the production of paper-covered wood veneer, the use of veneer woods which have higher moisture contents than heretofore. For example, wood veneers containing 250% moisture (250 lbs. of water per 100 lbs. of dry wood), are now useful. This feature makes possible the use of such heretofore unusable woods as green cottonwood.

Molds, stains, and the like bacteria growths are controlled on paper-covered wood veneer products when a glue of this invention is used.

A preferred glue of this invention is prepared as follows:

100 lbs. of 200-mesh oil-freed soya bean flour are mixed into 290 lbs. of water with lbs. of Vinsol resin. After thorough mixing, a solution of 7 lbs. NaOH in 20 lbs. of water is added to alkalinize the flour for use as a glue. A slurry composed of 13 lbs. of calcium hydroxide in 25 lbs. of water is then added. This lime slurry improves the water resistance of the glue. 3 lbs. of Dowside A (sodium orthophenyl-phenate) in 20 lbs. of water is added to the mass as a preservative.

In compounding the glue, it is important that the soya bean flour and the Vinsol be added to the water before the sodium hydroxide solution is incorporated.

It is also important to use very fine mesh soya bean flour relatively free from oil. Solvent extracted soya bean flour of 200-mesh or finer is suitable.

In general, the adhesives of this invention contain the following proportions of essential solids by weight:

Per Cent Alkali metal hydroxide 5 to 15 Vinsol resin 5 to Vegetable protein flour of 200-mesh or finer 65 to 90 One part of the above mixture of solids is used with three parts by weight of water.

From 5 to 15% of calcium hydroxide is a preferred but non-essential additive. From 1 to 5% of the Dowside A preservative is preferred but likewise is not essential.

A more preferred glue formula includes the fo lowing essential solids in proportions of parts by weight:

6 to 12% sodium hydroxide; 5 to 20% Vinsol; 68 to 89% soya bean flour of 200 mesh or finer.

As in the previous example, the above solids are used with 300% by weight of water and additives such as 10% calcium hydroxide and small amounts of preservative are preferred but not essential.

The soya bean content of the glue can be replaced with other vegetable protein flour of similar fineness, including locust bean flour, cottonseed flour, linseed flour, and the like. Such flour should be relatively freed from its vegetable oil content.

The Vinsol resin content of the glue has the capacity of improving the properties of the glue beyond expectations. It has been found, for example, that the incorporation of wood rosin into the glue in place of the Vinsol will not result in an adhesive that has a suitable drawing effect on the paper to pull the paper cover into the depressions, cracks, and other irregularities of low grade veneer. Further, the use of ordinary gum and wood rosins does not result in production of a glue having the tackiness or bond strength of the glue of this invention. As far as we are aware, the gasoline-insoluble, coal tar hydrocarbon-soluble, residual resin from wood is unique in producing the desired properties in the glue of this invention.

From the above descriptions it should be understood that the invention provides a glue of the alkalinized vegetable protein type containing a residual resin from wood that is soluble in coal tar hydrocarbons, insoluble in light petroleum hydrocarbons, and relatively freed from wood rosin. This residual resin imparts unexpected desired qualities to a soya bean-type glue.

It will of course, be understood that various details of the product may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

We claim as our invention:

1. A glue especially suitable for uniting paper to wood veneer and adapted to draw the paper into tight intimate contact with the wood which includes the following solids in parts by weight:

68 to 89% fine mesh soya bean flour;

6 to 12% sodium hydroxide;

5 to 20% coal tar hydrocarbon-soluble, gasolineinsoluble resin from southern long-leaf pine.

2. A glue comprisin the following solids:

5 to 15% by weight alkali metal hydroxide;

5 to 20% by weight residual resin from long-leaf pine soluble in coal tar hydrocarbons and substantially freed from petroleum hydrocarbon solubles;

65 to 90% by weight soya bean flour not appreciably coarser than 200 mesh.

3. A cold setting glue adapted to draw paper into intimate contact with wet wood containing by weight the following solids:

65 to 90% oil-freed 200-mesh or finer soya bean flour;

5 to 15% alkali metal hydroxide;

5 to 20% coal tar hydrocarbon-soluble, petroleum hydrocarbon-insoluble residual resin from wood;

5 to 15% calcium hydroxide;

1 to 5% preservative.

4. A soya bean glue consisting essentially of the following ingredients in parts by weight:

parts 200-mesh or finer soya bean flour;

10 parts coal tar hydrocarbon-soluble, petroleum hydrocarbon-insoluble residual resin from wood;

290 parts water;

7 parts sodium hydroxide in 20 parts water solution;

13 parts calcium hydroxide in 25 parts water;

3 parts sodium ortho phenyl phenate in 20 parts water.

5. A glue containing the following solids by weight: 65 to 95% vegetable protein flour, 5 to BEFERENQES CITED alkali metal hydroxide, and5to residual The following references are of record in the resin from wood that is substantially free from file Of this Patent! wood rosin and soluble in coal tar hydrocarbons 5 UNITED STATES PATENTS but insoluble in petroleum hydrocarbons.

6. A glue containing the following solids by Number Name Date weight: to vegetable protein flour. 5 to 1,854,703 Laucks et a1 1932 15% alkali metal hydroxide, and 5 to 20% re- 2,102,122 Lane 1937 sidual resin extract, said resin extract substan- 0 2253517 Heberer 1941 tially free from petroleum hydrocarbon soluble 2'336468 Cole et a1 1943 wood rosin, said resin extract having a melting point of about C. and an acid number of about 93.

MOSS B. CHRISTIAN. HORACE F. LADD. 

1. A GLUE ESPECIALLY SUITABLE FOR UNITING PAPER TO WOOD VENEER AND ADAPTED TO DRAW THE PAPER INTO TIGHT INTIMATE CONTACT WITH THE WOOD WHICH INCLUDES THE FOLLOWING SOLIDS IN PARTS BY WEIGHT: 68 TO 89% FINE MESH SOYA BEAN FLOUR; 6 TO 12% SODIUM HYDROXIDE; 5 TO 20% COAL TAR HYDROCARBON-SOLUBE, GASOLINEINSOLUBLE RESIN FROM SOUTHERN LONG-LEAF PINE. 